Furnace construction



p 93 c. T. 'CARLSON l;776,178

Y FURNAICE CONSTRUCTION Filed Dec. 21, 1927 9 2. BY ATTORNEY.

Patented Sept. 16, 1930 UNITED STATES PATENT OFFICE CARL THOMAS cARLsOn, OF NORTH GHATTANOOGA, TENNESSEE, ASSIGNOR TO THE CASEY-HEDGES COMPANY, OFGI-IATTANQOGA,TENNESSEE, A CORPORATION OF OHIO FURNACE OONsTRUOTI N Application filedDecember'Ql, 197.7. ,1 Serial No. 241,568.

The primary object of the inventionis to provide furnace structure for use particularly in the burning of pulverulent or finely divided fuel, by the use of which the ash or residue chamber of the furnace is maintained at substantially even and cool temperature Further, it is an object to so construct the furnace as to protect the walls of the hopper and ash pit, and to prevent the accumulation of refractory products of liquid ash so as to obviate clogging or choking of the furnace.

A still further object is to adequately protect against intense heat all surfaces over which the ash or residue of combustion travels in precipitation to the ash pit, and to extract the heat from such residue or ash during its travel and after it has accumulated in the pit. I

A further object is to provide means for the accomplishment of this heat extraction operation'associated directly with the water circulating system of the furnace, whereby the headerjlt at the lower end of the side heat extracted is utilized in raising the temperature of the water. I

Other objects and advantages will appear from the more detailed description which follows.

In the drawings:

Fig. 1 is a vertical sectional view taken through the lower part of a furnace struc ture involving the familiar water tube construction, and illustrating the arrangeemnt of cooling tubes in accordance with the invention,

Fig. 2 is a horizontal sectional view talten through the furnace with part of the casing and refractory material removed, and

Fig. 3 is a diagrammatic perspective view illustrating a preferable arrangement of water tubes.

Referring now to the drawing, l represents the side walls of the hopper, 5 is a p1t into which the ash or residue of combustion precipitates. This pit is relatively narrow,

and the walls 4 converge downwardly to communicate with the upper end of the pit. The bottom of the pit is closed by a gate 6 of any suitable construction and operating in any preferred manner. The upper ends of 56 the hopper walls 4 connect with the lower ends of the'side walls of the furnace, and it will be understood that combustion occurs within the chamber between these walls.

The hopper walls a are constructed in the I ordinary manner, that is, having refractory material 8 backed with insulating material 9 and held in place by the metal covering or casing 10. These walls have arranged thereon tubes 11 in relatively close relation and resting upon or within the refractory ma-. terial 8. These tubes are disposed parallel with the end walls of thefurnace, and connect preferablyr at their upper ends with headers 12 disposed at 'theupper end of the hopper and preferably at the juncture of the hopper walls with the side walls 71 Arranged adjacent to the juncture of the hopper walls 4 with the side walls 13 of the pit and extending the full length of the furnace are secondary headers 14:, with which the tubes 11 are iii-communication. Certain of the tubes 11 communicate directly with supporting said tubes, while others of the' tubes extend across the hopper and directly above the ash pit so as to communicate with the header 14 at the opposite side of the pit. Should all of the tubes of the series 11 extend across the ash pit to the headers at the oposite'side', a net-work of tubeswould occur at the topof the pit sufficiently close to constitute a support for a large part if not sub-' stantialy all of the ash or precipitate of com bustion, whereby the furnace would become, clogged. Tovobviate this occurrence, only a comparatively few of the'tubes are brought across the ash pit, and the furnace may be found to operate satisfactorily and in a high.- ly efficient manner by having one of each three or'four of the tubes cross in'the manner described. Thecrossingtubes are thus sufliciently spaced apart so as to-not in any way interfere with draft and to obviate the possibility of an accumulation of ash to such degree as to choke the furnace or render the ash diflicult of removal. r WVith the tubes thus arranged, the refractory wall of the hopper is eflectively pro-j I tected, and ash or other matter dropping thereon will slide down upon the tubes'or the refractory material to the pit 5. It will be noted that the inclination of the walls 4 is sufliciently steep to permit of ready precipitation. The ash and residue of combustion 5 in its downward travel upon or in rear proximity to these tubes will have the heat extracted therefrom by the relatively cool water in the tubes. Ash accumulated in the pit 5 will be cooled bythe crossed pipes at the upper part of the pit, as well as by the relatively cool water in the headers 14. Possibly, under normal conditions of operation, the accumulated ash will rise above the crossed tubes 11 at the upper end of the pit, and by reason of the intimate contact of these tubes with the highly heated ash, the heat will be readily extracted, and this heat thus utilized in raising the temperature of the water contained within the pipes 11 and the w headers 14.

The particular arrangement of the crossmg of the tubes insures proper cooling at the lower part of the furnace. and yet does not.

hinder the ashes from precipitating to the pit, or in falling through when the gate 6 is opened. Furthermore, this particular crossing arrangement of the tubes and the extension of tubes of one set to a header at the opposite side of the hopper furnishes a furnace structure possessing the desired flexibility with increased strength. As the upper part of the pit is comparatively narrow, a p

' ers of that wall and lying upon the latter, and

correspondingly short spanning length of tube over the ash pile is provided, and a more even'temperat'ure is thus obtained in this part of the tubewith a more uniform heat absorption.

The headers 12 are shown as having vertical tubes 15 connected thereto. In such case, 46* the upper ends of these tubes 15 will connect with headers 16, and from the latter steam and water would circulate back into the boiler (not shown). Such construction is by no means essential but is merely shown as one means of carrying out the circulation. Should the tubes 15 be dispensed with, water may be circulated directly into the boiler from the headers 12. WVater may be supplied to the tube system at any convenient or 503 desired place, pipe connections 20 being shown as introducing water to the header 14 at one side of the system. i The foregoing is a description of practical embodiments of the invention with alternate ?forms, however, it will be understood that the invention resides in the particular arrangement of tubes 11 associated with the hopper walls and with the ash pit, and any desirable means for carrying out circulation maybe reeolfsorted to without departing from the spirit of the invention.

'I-Iaving thus described my invention, I claim: V

1. In furnace structure, a hopperhaving oaf downwardly converging walls, a pit at the lower end of said walls and below the latter, tubes associated with each of said walls and extending toward said pit, and tubes of each Wall extending across said pit to communicate with tubes of the other wall; the crossing of such tubes being above the bottom of said pit.

2. In furnace structure, a hopper having downwardly converging walls, a pit communicating with the lower ends of said walls, headers at the juncture of the pit andhopper walls, tubes carried by said hopper walls, some of said tubes communicating with the adjacent header, and other of said tubes extending across said pit and in communication with the header in the opposite side thereof.

3. In furnace structure, a hopper having downwardly converging Walls, a pit communicating with the lower ends of said walls, headers arranged in parallel relation at the upper and lower ends of said walls, tubes on each wall connecting said headers ofthat wall, and tubes connecting the upper header of each wall with the lower header of the opposite wall.

A. In a furnace structure, a hopper having downwardly converging walls, pit walls communicating with the lower ends of said hopper walls and extending downwardly, headers at the upper and lower ends of said hoper walls, tubes on each wall connecting headother tubes on each wall communicating with the headers at the upper ends of that wall and extending downwardly thereon parallel to the other tubes and communicating with the lower headers of the opposite hopper walls.

In testimony whereof I aifix my signature.

CAR-L THOMAS CARLSON. 

